Kiwi lack typical bird characteristics such as flight feathers. They rely on smell and touch rather than sight, making them more akin to nocturnal forest-floor-dwelling mammals than nocturnal birds. The kiwi was probably created as a distinct bird ‘kind’ designed for ground-dwelling habitats.
Lack of flight features
For flight, birds need functional wings, well-formed feathers, a tail for flight control, light bones, and a strong breast bone that is able to withstand the pressures and tensions imposed on it by the flight muscles attached to it. The chicken-sized kiwi, however, has none of these (figures 1 and 2).
The kiwi’s wings, which are often referred to as ‘vestigial’,3 are ‘comically’ small; only 2–3 cm (about 1 inch). This lack of visible wings, which are hidden under their feathers, gives the kiwi the genus name Apteryx, meaning wingless.4
Kiwi feathers lack the hooks and barbs that keep most birds’ feathers in the neatly arranged vanes that contribute to the aerodynamics needed for flight (or swimming).5 Kiwi feathers hang loose, are fluffier and look more hair-like than other birds’ feathers (figure 3)—they were woven into treasured cloaks by the Maori pre-European settlers of New Zealand.6 Their mottled brown colour camouflages them in a range of habitats from forest floor and bracken scrub to tussock grasslands.7
To withstand the stresses of flight, most birds have a ‘keeled sternum’, which sticks out and anchors well-developed, powerful flight muscles. The keeled sternum is one of the largest bones in the skeleton of most birds and its shape varies with the life habits of a species (such as foraging strategies, or type of prey and how it is caught).10 The kiwi, ostrich, emu and cassowary belong to the only entire group of birds (ratites) that do not have a keeled sternum.11 None of the ratites can fly.12 Flightless members of other bird groups also have greatly reduced keels and rudimentary flight muscles, e.g. the Galápagos flightless cormorant10,13 and flightless rails. (In the case of rails some are thought to have developed, then lost, the ability to fly, whereas others are thought to have never developed that ability at all.14) The undeveloped flight muscles of the kiwi contribute to its unusual pear-shaped body.
Birds generally have hollow bones and limited leg muscle development. These features lessen the weight birds must lift for flight. Kiwis, however, have marrow-filled bones and exceptionally well-developed leg muscles (figure 2). The legs can contribute up to a third of their body weight!1 Kiwis’ powerful legs enable them to outrun humans, dig burrows and also defend themselves by kicking.
The kiwi’s large, four-toed feet have fleshy pads underneath (figure 3), which enable them to tread quietly as they search for food in the leaf litter and topsoil.12 They have large claws, which they use for digging.
Unlike other nocturnal birds, and contrary to what is expected according to evolutionary theory,15 the kiwi’s eyes are small. The optic nerve and parts of their brain related to sight are much smaller than in most birds. Their eye sockets are divided into large nasal cavities like in most mammals, rather than being separated by a plate as in most birds.1
The kiwis’ sense of smell is extremely well developed. The sense of smell processing area of their brain (the olfactory bulb) is the second largest among all birds relative to the size of their whole brain.16 Kiwis have up to six times as many olfactory receptor (OR) genes as other bird species17—OR genes relate to the sensory neurons in the olfactory surface cells that enable the sense of smell. The number of OR genes is thought to be related to how many different scents an animal can detect. In mammals, species that depend most heavily on smell rather than other senses also have larger numbers of OR genes. Kiwis use their sense of smell, rather than sight, to guide them to their food. Their loud nocturnal snuffling is equivalent to them blowing their noses to clear them!16
Kiwis are the only birds with nostrils at the tip of their long, curved beak8,16 rather than close to their skull. The tips of their beaks also have ‘specialized vibration/pressure-sensing nerve endings’, which also help them find their food.8,16
They also use their beaks as a probe and a lever to catch their prey. As they walk along, they tap the ground with their beaks, probing the soil and leaf litter and sniffing loudly. The kiwi beak has an unusual hinge arrangement so that the tip of the upper beak overlaps the lower beak.16 Kiwis sometimes do bizarre ‘headstands’, kicking their legs up in the air and driving their beaks deeper into the ground. To enlarge a hole, they move their beaks back and forth. Once a kiwi has a worm grasped in its beak it will be very careful not to break it. Sometimes they will get the worm out by slow, gentle pulling. Other times the kiwi will hold completely still until the worm relaxes its grip on its tunnel, then give a quick tug to extract it.16
Unlike other birds kiwis have cat-like whiskers at the base of their beaks (figure 3) which may help with night time navigation.2
How did the kiwi get to New Zealand?18
New Zealand is isolated in the South Pacific, 2,000 km east of Australia. Being so isolated New Zealand has developed a unique flora and fauna, so much so that it has been called a ‘biological ark’.19 It has the largest number of endemic species of plants and animals in the world, including the kiwi.
There are three evolutionary theories as to how the flightless kiwi arrived in New Zealand:
The ancient ancestor theory proposes that the kiwi lived 60 Ma before New Zealand supposedly broke away from Australia and Antarctica.20 [This theory presupposes long ages.]
The walking theory proposes a series of islands that rose and sank across the Tasman Sea between Australia, New Caledonia and New Zealand throughout the last 50 Ma and that kiwi walked across this series of ‘stepping stone’ islands.19 [The string of islands would have had to rise and sink in exactly the right sequence and position close enough for the flightless kiwi to ‘island hop’.]
The flying kiwi ancestor theory proposes that kiwi ancestors could fly but lost that ability since arriving in New Zealand.19 [The ancestors would have had to ‘evolve’ all the many features necessary for flight (keeled sternum, wings, vaned feathers, tail, preening gland, hollow bones, etc.) and then lose them all again. This is an unrealistic stretch even for the most generous evolutionary timescale.]
A creationist perspective may be that the kiwi, and perhaps its ratite relatives, was created as a distinct bird ‘kind’, perfectly well designed for their ground-dwelling habitats and life styles. Two ancestors of the created kind would have been on Noah’s Ark. But how, then, did they get from the ark landing site to New Zealand?
There is significant evidence that before the Flood there were massive floating ecosystems of lycopod forests that supported a wide variety of other species. Such floating ecosystems are possible sources of many carboniferous coal seams around the world.21
Before the Flood such floating ecosystems may have been positioned about the polar regions. Pre-Flood, there were no ice caps as the whole earth’s climate was temperate. However the polar regions would still have experienced less sunlight time and intensity than the equatorial regions, making them a suitable environment for both the lycopod forests and the kiwi.
During Noah’s world-wide Flood, huge hydrological forces could have torn apart the massive floating ecosystems. During the abatement period fragments of these ecosystems may have floated on the receding waters and been carried around the globe on currents.
If this is so, ancestral kiwis could have wandered onto a floating ecosystem fragment, or fragments, and been carried to New Zealand, where they were able to thrive for several millennia as ground-dwelling birds in the predator-free environment.
As the post-Flood climate became more extreme and the salinity of the oceans increased, the floating ecosystems died out, perhaps contributing to the coal reserves on the west coast of New Zealand.
According to current evolutionary theory, there is no consensus as to whether kiwis (and ratites) were previously able to fly and lost that ability, or never developed the ability. The many extraordinary similarities between kiwis and mammals are also interpreted as evidence of ‘convergent evolution’, a ‘one-off evolutionary design’ among birds.4 But evolution by design is a contradiction in terms. The kiwis’ unique combination of physical, physiological, genetic, and behavioural characteristics strongly suggests that they were never able to fly; nor have they ‘evolved’ their unique array of mammal-like features. A far more straightforward and logical conclusion is that they were interestingly and appropriately designed with all the genetic information they would need to occupy their unique niche in the ecology of New Zealand.
References and notes
- Honorary mammals, kiwisforkiwi.org. Return to text.
- Story: Kiwi Page 1—A remarkable bird, teara.govt.nz. Return to text.
- Holzapfel, S.A., et al., Kiwi (Apteryx spp.) recovery plan 2008–2018, Threatened Species Recovery Plan 60, p. 10, doc.govt.nz/upload/documents/science-and-technical/tsrp60.pdf. Return to text.
- Kiwi facts & characteristics, kiwisforkiwi.org. Return to text.
- Safarti, J., Refuting Evolution, Creation Book Publishers, p. 64, 1999. Return to text.
- Yirka, B., DNA of kiwi cloaks reveals history of Maori feather trade, physorg.com, May 2011. Return to text.
- Feathers like hair, kiwisforkiwi.org. Return to text.
- Holzapfel et al., ref. 3, p. 10. Return to text.
- Preen gland, britannica.com. Return to text.
- Seabird Osteology, Breastbone or sternum, shearwater.nl. Return to text.
- Ratis means ‘raft’ in Latin; a boat without a keel. Return to text.
- Kiwi are ratites, kiwisforkiwi.org. Return to text.
- Cosner, L. and Sarfati, J., The birds of the Galápagos, Creation 31(3):28–31, June 2009; creation.com/galapagos-birds. Also see Flightless cormorant, people.rit.edu, October 2008. Return to text.
- Lowe, P.R., VII.-A Description of Atlantisia rogersi, the Diminutive and Flightless Rail of Inaccessible Island (Southern Atlantic), with some Notes on Flightless Rails, Ibis 70(1):99–131, 1928. Return to text.
- Martin, G.R., Wilson, K.-J., Wild, J.M., Parsons, S., Kubke, M.F. and Corfield, J., Kiwi Forego Vision in the Guidance of Their Nocturnal Activities, PLoS One. 2(2):e198, February 2007. Return to text.
- An unusual beak, kiwisforkiwi.org. Return to text.
- Birds Have A Good Sense Of Smell, ScienceDaily, sciencedaily.com, July 2008. Return to text.
- Editor’s note: for an alternative view see: Catchpoole, D., Of Moas and Men, Creation 33(1):12–14, January 2011; creation.com/moas. Return to text.
- Welcome to Ara Roa, araroa.co.nz. Return to text.
- How kiwi came here, kiwisforkiwi.org. Return to text.
- Scheven, J., The Carboniferous floating forest—an extinct pre-Flood ecosystem, J. Creation 10(1):70–81, April 1996; creation.com/floating-forest. Return to text.
The picture of kiwi feathers reminds me of some emu feathers I used to own. Are they similar?
The picture of the dissected kiwi also looks rather like a small distorted emu (apart from the very long beak), adding weight to your suggestion that they are the same created kind.
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Why couldn't this be a bird that has lost its ability to fly? I think it would be strange if it was designed with that type of feathers and a 1 inch wing.
Has their genome been analysed and compared to genome of flying birds or to establish if their lack of flight is due to mutations?
Yes, you will find that with an internet search.
The article supposes kiwis were designed as they currently are. But given all their 'deficiencies' compared to other birds, would it be reasonable to suggest they are actually degenerate forms that have suffered several 'loss' mutations?
I'm not sure if you think that the writer suggests the kiwi always looked this way because we can't know that for sure. However, we do see variation within the limits of the created kind. See Speciation questions and answers.
Thanks, another great article. Just one comment: You say, 'Unlike other birds kiwis have cat-like whiskers at the base of their beaks (figure 3) which may help with night time navigation.'
Actually 'caprimulgiformes' like the Nightjar and Poorwill have 'whiskers', if mainly for guiding night flying insects into their wide maws.
Keep up the good work, and MARANATHA! Philip
This article leaves me wondering after several other details of the kiwi compared to flying and ex-flying bird with which I am familiar. I believe flying birds have nucleated erythrocytes (i.e. red blood cells with DNA) because of the lack of bone marrow which produces erythrocytes in mammals. This leaves me wondering if kiwi's have nuclei in their erythrocytes. The next question I have regards the lungs: do kiwis have aveolar or brachiotubule/air sac breathing systems? The latter tend to be associated with marrow-filled bones as well. These features, along with many lacked by the kiwi, are all featured on flying birds, but are not exclusive to them. I've memorized a list of features that flying birds seem to require; all flying birds have all of them, and seeing them all in a non-flying bird (e.g. the chicken) tells me that it probably once flew. The carina (keel-sternum), pectoralis (breast muscles), nucleated erythrocytes, pneumatized bones, asymmetric barb-locked feathers, the uropygial gland, brachiotubule lungs, and possibly the crop/gizzard digestive tract and uricotelic metabolism all appear to be part of God's design for the flying birds. How many are different or missing on the kiwi?
A simpler question is whether God made the ratites on the fifth or sixth day of creation week. The sixth day seems far more consistent with their inability to fly.
Do birds need tail feathers?
They certainly fly better with them, but they can fly without them.
I once rescued a blackbird trapped inside a net. In the process of setting it free, I finished up with ALL its tail feathers in my hand. Despite this, it was ably to fly where it wanted. Its flight was somewhat ungainly flight, but its tiny bird-brain was clearly able to compensate for the sudden loss of all its tail feathers.
That sounds like good design with built in redundancy. How many aeroplanes can fly when their tails are missing? How many aeroplanes can find their own fuel and reproduce themselves?